1. Field of the Invention
Generally speaking, when a document comprises character informations and picture informations, the base for the character informations is in most cases brighter than the base for the picture informations. In a document containing the abovementioned two sorts of informations, the character informations are more important than the picture informations. Therefore, in case the document of the abovementioned nature is recorded by a recording device such as a micro-film camera device, more legibility is demanded on the character informations than on the picture informations.
2. Description of the Prior Art
For example, the light-metering operation on a photographic object in the conventional recording device such as a micro-film camera device which photographs those informations contained in books and documents on microfilm has been done in most cases by averaging reflected light from a region 2, as designated in FIG. 1 of the accompanying drawing, in the entire photographic object 1 with use of a single light receiving element, and the like. Based on this light-metering, the exposure quantity is determined for the photo-taking operation. However, when a photographic object containing therein the character informations printed in black on a white background and the picture informations with more portions in grey or black therein as the background is subjected to the light-metering operation by such conventional method, the resulting image is very much influenced by the picture information section. On account of this, it becomes difficult to obtain an appropriate exposure quantity for the character information section, which inevitably results in such disadvantage that, when the photographic object is filmed, the character information section yields an inferior image contrast due to excessive exposure quantity, and the film thus obtained is hard to read and unsuitable for practical use. Also, in case of projecting the optical informations on the micro-film having both picture information section and character information section of one and the same film frame onto an image projecting screen for display, if the exposure quantity is determined by the conventional method, the image contrast at the character information section tends to become inferior.